calling all knowledgeable 2smokers, brace your self .. 3d ignition questions!

Discussion in '2 smokers' started by Reino, May 24, 2012.

  1. Reino

    Reino Been here awhile

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    I am considering the use of a knock sensor as a fail safe, the control unit can utilize all the the mentioned sensors in this thread and then some.
    #21
  2. Reino

    Reino Been here awhile

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    The only sucky thing about going into detail with 3d ignition is that I would have to redo every thing if I use a different pipe. Even if i use the same type of pipe there are still small production variances between the same series pipe.

    I will probably make a map on the edge and dial it back slightly to make it more tolerable of production variances and normal wear(dings).
    #22
  3. Twin-shocker

    Twin-shocker Long timer

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    Atmo conditions change from day to day, and if you want max power from a 2T race motor, you will need to try various different maps to take this into account. I would imagine its going to take 2-3 days on a dyno (with an experienced operator) to come up with baseline maps, and costs are going to be relatively high, especially so if motor damage occurs.
    #23
  4. Reino

    Reino Been here awhile

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    the ignition map resolution is 12*12 (i can change it to focus more on rpm than on load or viceversa).

    I am going to run 20 degrees advance at 100% load and 30 degrees at 0% load. The dyno i am going to use has to be able to hold the engine at a certain load and rpm, than i am going to test each ignition cell till it gives me max power. And as sed before i will dial it back.

    Then temp and atmospheric pressure testing. I think temp is going to play a bigger role than pressure, but we will see. To isolate the variables i am going to test temp at the same location i did the initial map by manipulating the IAT using a heating source. After testing many heat ranges i will determine is the advance decrease per temp range is linear or not so that i can predict all the ranges.

    I will then factor in temp and pressure(?) into the ignition map.
    #24
  5. Twin-shocker

    Twin-shocker Long timer

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    If you are doing power runs on a dyno you will find pressure makes a very big difference. Serious 2T racers will also change jetting to suit atmo conditions, and changes here are directly related to ignition settings, and of course heat.
    #25
  6. Reino

    Reino Been here awhile

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    I am not going to need to change jetting, that is the other half of my project and also the easiest part.

    The most difficult thing of a 2stroke is ignition. From what i have read is that as long as the a/f ration stays the same it wont hamper the ignition, but fuel and air temp is directly related to detonation (as well as combustion chamber design, but my bike is relatively modern).:deal

    I don't think i will go past 30 degrees advance when at full load (anything can happen, keep it safe).

    For testing proposes i am going to ran at 12.5/1 a/f ratio than after logging during real world testing (riding the damn thing)
    i am going to lean out my cruising load and rpm and back off of the (less advance) corresponding ignition cell's.

    I have to thank you for contributing to my tread Twin-shocker.:thumb
    If i could i would buy you a beer.:beer
    #26
  7. Twin-shocker

    Twin-shocker Long timer

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    If you dont change jetting to accord with atmo conditions when running on the dyno, you will be losing a fair amount of power, but more importantly will have no real idea whether or not changes to ignition are simply compensating for weak or rich mixture rather than making the motor work better.

    You will also have major problems if the squish clearance has not been corrected, as this will mean greatly increased piston crown temperature, and increase the chances of detonation, as well as reducing MSV.

    Effectively tuning a 2T motor is in many ways far more complex than a 4T, due to the amount of difference that will result from changes in heat/pressure, and is certainly not something for someone without a fair amount of previous experience of this type of work.
    #27
  8. Reino

    Reino Been here awhile

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    The second part of this project entails replacing the carb with something more suitable. No more jets to worry about.

    Checking the squish clearance is something i was planning to do before i start my project. I was also planning on engine rebuild and setting my PV correctly.
    #28
  9. Twin-shocker

    Twin-shocker Long timer

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    If you intend to add direct FI to your motor, you are going to need electronics rather more complex than those you have currently.

    Might be better to either take on board the fact you are going to need to spend time getting the fueling right, in order to get any worthwhile results from alterations to the ignition, or think about abandoning the whole project?

    Up to now very few people have been able to get injection working properly on 2T motors, and I get the feeling that the only competition application running FI currently is on the Ossa trials bikes?
    #29
  10. Reino

    Reino Been here awhile

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    I don't want to add direct fi, i want to add port fuel injection (throttle body injection) fueling is not a big problem i can maintain it at 12.5/1 a/f ratio through out the 12*12 fuel map (closed loop operation) and alter it later after i know in which rpm and load cell i use for cruising.

    The biggest problem i had was ignition, because it was an unknown when concerning 3D maps.

    examples

    banshee
    http://www.youtube.com/watch?v=e1WHVVT6d9c

    suzuki gt250
    http://www.youtube.com/watch?v=_aAfptmI4jU

    cr500
    http://www.youtube.com/watch?v=TE5ENcMH1ZI
    http://www.youtube.com/watch?v=Y91Jms6MyCY

    There's also an rd350lc

    I did not really want to bring up the fact that i am looking to fuel inject a 2stroke because of bad criticism.
    #30
  11. Twin-shocker

    Twin-shocker Long timer

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    I wonder why you feel that you are likely to succeed when manufacturers such as Bimota failed with port injection? Direct injection is certainly feasible though, and I would imagine a similar design to that used on various scooters could be used.

    There are various reasons why port injection is not likely to work, but the main one is that without very sophisticated and costly electronics, its not going to be possible to improve on a properly jetted common or garden carb set up.
    #31
  12. Reino

    Reino Been here awhile

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    The reason bimota failed was development, they wanted to use semy direct injection like skeedoo but they had 6 month's or so development. I cant use there injection method, because at idle (800 rpm) i calculated that the injector only has 0.83ms to inject the required fuel and that is not enough time for a low pressure system (3.5bar) to inject the fuel.

    The advantages of port fuel injection is as follows

    better atomisation at any throttle opening
    larger throttle body without sacrificing low down torque
    Adjustability
    barometric compensation

    Disadvantage

    more weight
    cost


    The reason manufactures do not develop 2t efi is simple, what are the modern 2strokes known for:
    1-simplicity
    2-lightweight
    3-low price compared to equivalent 4stroke

    Those are the selling points.


    For a pure mx bike i would not develop this. on a mx track the disadvantages outweigh the advantages.little altitude change, wide open throttle most of the time and short races compared to enduros.
    #32
  13. Twin-shocker

    Twin-shocker Long timer

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    I would be very interested to hear more about any successful 2T port EFI systems, especially anything related to how the degree of precision provided by a simple carb, can be improved on.
    #33
  14. Reino

    Reino Been here awhile

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    Everything i have read on efi port 2t (posted examples) is that there is an increase in power. smoothness, lowdown torque, throttle response (ignition) and general rideability.

    When i started doing research on the topic(about 4 years ago) i wanted to do semy direct injection, but the power requirements and weight were to high(high pressure fuel pump).

    When i have all the required parts i will start testing and when it is done, advrider is the first place i will show what i have accomplished.
    Parts just for the efi system (sensors eco fuel pump battery regulator etc) and dyno time will cost me about 1850 USD.
    #34
  15. Twin-shocker

    Twin-shocker Long timer

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    I was wondering if anyone has actually managed to get 2T port EFI working and if so where to find info on this? Also any pics or further details on the motor you intend to modify, and is it for road or race use?
    #35
  16. e rock

    e rock Been here awhile

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  17. Twin-shocker

    Twin-shocker Long timer

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    #37
  18. Reino

    Reino Been here awhile

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    They have been doing banshee efi for a while now, i think it its flat track and drag racing, but also for just playing around. Then there is the fuel injected cr500.

    All of them are custom built systems. there are no kit's except for the banshee. Its extremely expensive so most guys use micro or megasquirt ecu witch works well.

    Its a fully programmable universal ecu.

    I think the kit is only supposed to be used on scooters or something in that line(i came across it a while back during my research).
    #38
  19. Reino

    Reino Been here awhile

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    my engine i want to convert is a 2006 ktm 250sx engine

    Things i am planing is just an engine rebuild and cleaning the production defects in the ports, smoothing the intake to the crankcase and at he same time reducing crankcase volume. Than put everything together and make shore everything is in speck (squish, pv max height).

    At the moment the engine is standerd in every way except my stator and pipe(full procircuit system, expansion chamber platinum 2).
    #39
  20. Twin-shocker

    Twin-shocker Long timer

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    I would suggest steering well clear of anything to do with MBE Motorsport................their products seem to largely consist of Chinese rubbish of the type sold on Ebay!

    Maybe an idea to look closely at the areas you feel are lacking or need to be improved on your bike, and investigate how to go about alterations using tried and tested parts and methods?
    #40